Process for introducing mercury into discharge tubes and apparatus therefor



i fi 3 M. @AREzss ET AL PROCESS FUR INTRODUCING MERCURY INTO DISCHARGE TUBES ANE APPARATUS THEREFOR Filed June 9, 1930 Inventors: V Max Bareiss,

Erich Wiegand.

Their Attorne.

Watented Apr. 2%, W32

rerun e MAX BAREISS, OF WATERTOWN, MASSACHUSETTS, AND ERICH 'WIEGAND, OF BERLIN- WAIDMANNSLUST, GERMANY, ASSIGNORS T0 GENERAL ELECTRIC COMPANY, A

CORPORATION 015 NEW YORK PROCESS JFOR INTRODUCING MERCURY INTO DISCHARGE TUBES AND APPARATUS l THEREFOR Application filed June 9, 1930, Serial No. 459,862, and in Germany August 21, 1929.

The. present invention relates to processes and means for introd ucing mercury into electric discharge tubes.

It has been found desirable to introduce mercury into various types of electric discharge tubes in order to improve the properties of the discharge. Heretofore, it has been the practice to place a measured quantity of mercury in a-receptacle communicating with the vacuum .system to which the tube is connected, and to introduce the mereury mechanically into the tube after evacuation. This practice was open to the objections of causing spillage of the mercury, also as being injurious to the health of the operator, and moreover, was not suited to quantity production. methods.

. -Wehave discovered that it is possible to evolve mercury of sufficient purity for the purpose in view from certain mercury compounds by means of suitable reducing agents without the production of undesirable conversion products. a Our discovery lends itself to the release by external heating, ,of mer cury in sufiicient quantity for one tube from a small solid mercury-containing body or pellet. Inasmuch as the mercury is handled as a stable, solid member and is not released until placed within the vacuum tube, i. e. in situ, the objections" set forth are overcome.

The mercury compounds which have proved efiicient and which are not decomposed at the usual temperature of the bakeout are, for example, mercury tungstate and mercury sulphide. Suitable reducing agents are iron, nickel, magnesium and other metals.

. A preferred method is to mix the two materials in powdered form and in suitable proportions, and to compress them by means of well-known machinesdnto small pellets of certain size orweight. The pellet thus obtained may be placed on a metal extension of the anode of each tube and heated by high frequency after the tube is evacuated. Thus, in the figure, the pellet 1 is shown as being supported on a metal extension 2 which is attached to the leading-in conductor 3 of the anode 4. In addition to the anode 4, the envelope 5- contains a cathode 6 of suitable construction, e. g. a cylindrical member indirectly heated by an internally located filament and may also contain a grid member.

{not shown) for electrostatic control purposes, as is well-known in the art.

In cases in which a particular vacuum is to be obtained or in which the pumping period is to be shortened, it may be desirable to add an excess of magnesium to the mixture which forms the pellet, the said magnesium being evaporated with the remainder of the materials for the purpose of eliminating gas residue.

Some of the advantages of our improved process of introducing mercury over the evolved only when in situ within the tube and the mercury compounds used in this process are entirely stable at normal temperatures and therefore do not evolve any mercury.

In order to avoid the evaporation of the mercury compounds (for example mercury sulphide) which may detrimentally affect the appearance or properties of the tube by the formation of a coating or the like, it may be desirable to coat the reaction mixture or compound with an absorbing layer; the latter' may consist preferably of the same ma- 1 terial as the reducing agent employed, for example, pure iron powder, nickel powder or the like. It may also be desirable to remove the residue left in the tube after reducing the mercury in order to prevent the damaging action of the residue upon the mercury vapor. To this end, the mixture or compound may be placed in an extension tube which is fused off after the mercury vapor has been derived.

What we claim as new and desire to secure by Letters Patent of the United States, is: 1. The method of introducing mercury into the envelope of an electric discharge device which consists in forming a body containing mercury as a solid compound capable of bein reduced, inserting the solid body within tie envelope and treating the body to cause a reduction of the compound whereby'mercury is evolved.

2. The method of introducing mercury into the envelope of an electric discharge device, which consists in mixing mercury in solid compound form with a reducing agent, positioning the mixture within the envelope and heating the mixture to cause a reduction of the compound whereby mercury is evolved.

3. The method of introducing mercury into the envelope of an electric discharge device which consists in mixing a mercurycontainin compound with a material which is adapted to derive mercury from the compound when subjected to heat, compressing the mixture into pellet form, placing the ellet in the envelope, sealing and evacuat- 1n the envelope, and finally heating the pe let to evolve mercury.

4. The method of introducing mercury into the envelope of an electric discharge device which consists in mixing mercury sulphide with a reducing agent, compressing the mixture into pellet form and placing the pellet within the envelope, sealing and evacuating the envelope and finally heating the pellet to evolve mercury.

5. The method of introducing mercury into the envelope of an electric discharge device, which consists in mixing mercury sulphide with iron powder, compressing the mixture into pellet form and placing the pellet within the envelope, and finally heating the pellet to evolve mercury.

6. The method of introducing mercury into an electric discharge device provided with electrodes, said method including the steps of mixing a mercury-containing compound with a material adapted to derive mercury from the compound when subjected to heat, compressing the mixture into pellet form, securing the pellet to an electrode and heating the electrode and pellet thereby to cause reaction between the materials of the pellet and to cause the evolution of mercury.

7. In an evacuated envelope, a mixture of a mercury-containing compound and a reducing agent.

8. In an evacuated envelope, a solid, coherent body consisting of a mercury-containing compound mixed with a reducing agent.

9. In an evacuated envelope, a solid, coherent body consisting of a mercury-containing compound mixed with a reducing agent and coated with a. layer of mercury-absorbing material.

10. An electric discharge device comprising an evacuated envelope, electrodes within said envelope, a pellet consisting of mer cur sulphide and iron attached to one of sai electrodes, said pellet being adapted to be heated to evolve mercur In witness'whereof, we have hereunto set our hands this 22nd day of April, 1930, and this 22nd day of May, 1930.

MAX BAREISS. ERICH WIEGAND.

iao 

